1. Technical Field
The present invention relates to prevention of oblique tightening of a fusible link directly mounted on a battery, and particularly to a protective cap for prevention of oblique tightening constructed so that a nut can be prevented from being obliquely tightened.
2. Background Art
A vehicle of an automobile is equipped with a battery as a power supply source, and a fusible link with a built-in fuse is electrically connected to a battery post of the battery through a battery terminal. As the fusible link directly mounted on the battery, for example, a fusible link described in JP-A-2000-331591 as shown in FIG. 18 is used conventionally.
FIG. 18 is an exploded perspective view of a fusible link directly mounted on a battery described in JP-A-2000-331591. In FIG. 18, a fusible link 30 directly mounted on a battery is electrically connected to a battery post 10P of the battery 10 through a battery terminal 20.
The battery 10 has a rectangular parallelepiped and the battery post 10P is erected in the vicinity of the upper end. The battery terminal 20 is crimped onto this battery post 10P.
The battery terminal 20 includes a crimp hole 20H for inserting the battery post 10P of the battery 10 in the center, an adjusting screw 20N for adjusting a diameter of the crimp hole 20H small and large, and a power source side stud bolt 20S inserted into a connection hole 32Ah of a power source side terminal block 32A of the fusible link 30.
The fusible link 30 is constructed of a fuse body 32 and a resin case 34 with which this fuse body 32 is partially covered by resin molding, and the apex of the fusible link 30 is covered with a protective cap 50. The fuse body 32 is made by punching one conductive plate, and is constructed of the power source side terminal block 32A with a rectangular shape, a narrow fusible body 32F joined to the power source side terminal block 32A, and substantially a rectangular wire harness side terminal block 32B joined to the fusible body 32F. The power source side terminal block 32A, the fusible body 32F and the wire harness side terminal block 32B are arranged on substantially the same plane. The fusible body 32F is not shown, but is presence inside a transparent cover 30F.
The connection hole 32Ah is formed in the power source side terminal block 32A and also, both of the front and back portions are excluded from the resin case 34 to a range corresponding to space into which a tool (an impact wrench) is inserted around the connection hole 32Ah.
The wire harness side terminal block 32B has a bolt hole 32Bh, and a stud bolt 32S protrudes upward (the side opposite to the battery) in this bolt hole 32Bh.
The resin case 34 exposes the front and back sides of the power source side terminal block 32A and the front side of the wire harness side terminal block 32B in the fuse body 32 from the resin case 34 and thereby, the exposed portion is formed as an electrical connection. Also, the front and back sides of the fusible body 32F are exposed from the resin case 34, and the transparent covers 30F are respectively disposed over the front side of the fuse body 32 and under the back side of the fuse body 32, and appearance of a fusion part of the fusible body of the inside can be visually checked through the transparent covers 30F. A heat-radiating fin is formed on a surface of the resin case 34. The resin molding is performed after the stud bolt 32S is attached to the bolt hole 32Bh of the wire harness side terminal block 32B.
A wire harness side terminal 40 is fitted into the stud bolt 32S and a nut is screwed to the stud bolt 32S and thereby, the wire harness side terminal 40 is electrically connected to the stud bolt 32S.
The protective cap 50 is means for covering the fusible link 30, and is molded by resin. This protective cap prevents atmospheric dust etc. from entering and also prevents the human body from making contact to get an electric shock or cause an electric leak.
A conventional procedure of assembly in a vehicle is performed as described below.
First, the battery terminal 20 is fixed to the battery post 10P.
Next, the power source side stud bolt 20S of the battery terminal 20 is inserted into the connection hole 32Ah of the power source side terminal block 32A of the fusible link 30, and the nut N is screwed and tightened to the power source side stud bolt 20S, and the power source side terminal block 32A is electrically connected to the power source side stud bolt 20S.
Finally, the protective cap 50 is fitted into the fusible link 30 from the upper portion of the fusible link 30.
Thereafter, at the time of use, the wire harness side terminal 40 is fitted into the stud bolt 32S of the fusible link 30 and the nut is screwed to the stud bolt 32S and thereby, the wire harness side terminal 40 is electrically connected to the battery 10. In that case, the protective cap 50 may be detached temporarily, but it is desirable to be constructed so that a hinge is previously formed in a region of the protective cap 50 corresponding to the stud bolt 32S of the fusible link 30 and only the portion is turned around the hinge at the time of connection and only the region of the stud bolt 32S can be exposed.
In the case of fixing the battery terminal 20 to the battery post 10P, the battery post 10P is inserted into the crimp hole 20H of the center of the battery terminal 20 and the adjusting screw (nut) 20N is tightened from the side of a horizontal bolt, so that there is a low possibility that gravity acts on the nut and oblique insertion is performed and also, even if oblique tightening of the bolt and the nut occurs and the oblique tightening is noticed, a tightening method for decreasing a diameter of the crimp hole 20H is adopted, so that a tightening force is still small and the nut is returned and the tightening can be retried.
Also, since the wire harness side terminal 40 is fixed to the stud bolt 32S of the fusible link 30 in a place overhanging from the end of the battery 10, a sufficient visual check can be made, so that there is a low possibility that oblique tightening of the bolt and the nut at the time of tightening occurs and also, even if oblique tightening of the bolt and the nut occurs and the oblique tightening is noticed, a tightening force is small, so that the tightening can be retried.
On the other hand, in the case of fixing the nut N to the power source side stud bolt 20S of the battery terminal 20 through the connection hole 32Ah of the power source side terminal block 32A of the fusible link 30, the bulk of the resin case 34 becomes an obstacle and it is less visible and also, the nut N is inserted into the power source side stud bolt 20S in a perpendicular direction, so that it is difficult to notice oblique insertion and also tightening is performed by a large pressing force, so that when oblique tightening of the bolt and the nut occurs and the oblique tightening is noticed, an abnormal groove is formed in the bolt or the nut and it is difficult to retry the tightening.
Also, inventions for preventing an increase in resistance by oblique tightening of a bolt and a nut at the time of tightening have been proposed before now.
The first invention is that a peripheral wall is formed in the periphery of an erected bolt and when work is done with a torque wrench, the peripheral wall regulates oblique travel of the torque wrench so that the torque wrench does not become oblique.
The second invention is that the top of a bolt of a tightening part is changed into a long dog point shape and a nut is temporarily set at this top (see JP-A-10-92484).
However, these inventions for preventing the oblique tightening have poor workability and also, still have a possibility that the oblique tightening occurs due to deviation of a tool angle in the case of tightening the bolt and the nut.